When A Lioness Fights by kayly-silverstorm over on ff.net, don't know if she's on this site though.. it is a completed story..
The other spy by Hermione snape on ff.net, this one isn't done and I'm not sure if it's here as well..
The Last Spy by Sylphides on ff.net, completed.
secrets in the dark by imslytherinatheart on ff.net, completed
these are a few that I know of, although not sure if she's actually in the inner circle or Snapes handler with the Last spy or not, it's been so long since I've read it.. the Lioness one is one of my favorites...